The present invention relates to metal-corrosion inhibitors, metal-corrosion inhibition cleaning compositions, and metal-corrosion inhibition cleaning systems and methods of using the metal-corrosion inhibitors. The present invention relates to the applications applied to semiconductor devices containing delicate metal such as copper (Cu), tungsten (W), titanium (Ti), tantalum (Ta), cobalt (Co), and aluminum (Al), specifically copper interconnecting structures.
As microelectronic fabrication integration levels have increased and patterned microelectronic device dimensions have decreased, it has become increasingly common in the art to employ copper metallizations, low-k and high-k dielectrics.
In the manufacturing process, a thin film of photoresist is deposited on a wafer substrate, and then circuit design is imaged on the thin film. Following baking, the unpolymerized resist is removed with a photoresist developer. The resulting image is then transferred to the underlying material, which is generally a dielectric or metal; by way of reactive plasma etch gases or chemical etchant solutions. The etchant gases or chemical etchant solutions selectively attack the photoresist-unprotected area of the substrate. As a result of the plasma etching process, photoresist, etching gas and etched material by-products are deposited as residues around or on the side wall of the etched openings on the wafer or substrate.
Removal of these etches and/or ash residues following the plasma etch and/or ashing process has proved problematic. Failure to completely remove or neutralize these residues can result in the absorption of moisture and the formation of undesirable materials that can cause corrosion to the metal structures. The circuitry materials are corroded by the undesirable materials and produce discontinuances in the circuitry wiring and undesirable increases in electrical resistance.
Furthermore, in the metal wiring formation utilizing chemical mechanical polishing (CMP), both the surface and the back of a wafer are markedly contaminated with the polishing agent remaining after the metal polishing, a polishing scrap produced by the polishing and metal impurities contained in the polishing agent and the polishing pad, and therefore it is inevitable to clean the surface thereof after the polishing.
In general, in order to remove particles present on a wafer surface, it is desired to carrying out a cleaning with an alkaline solution, because it is important to inhibit re-adhesion of particles once removed out of the surface thereof.
While, in order to remove metal impurities effectively, it is desired to carry out the cleaning with an acid solution having a strong metal dissolution power. However, as is known, a metal is subject to corrosion with these alkaline and acid solutions. Therefore, in the case where the wafer surface on which the metal wiring lays bare is cleaned with these solutions, there is usually a problem that the metal surface after the cleaning is subjected to corrosion, thereby causing increase of a wiring resistance and moreover a breaking down of the wiring.
An attempt to use corrosion inhibitors to avoid the metal-corrosion has been made.
The various prior art compositions have drawbacks that include unwanted removal of metal or insulator layers and the corrosion of desirable metal layers, particularly copper or copper alloys features. Some prior art formulations employ corrosion inhibiting additives to prevent undesirable copper metal corrosion during the cleaning process. However, those conventional corrosion-inhibiting additives typically have detrimental effects on the cleaning process because those additives can interact with the residue and inhibit dissolution of such residue into the cleaning fluid.
For example, the passivator chemistries, such as aromatic hydrocarbon compounds, for example, benzotriazole and 5-methylbenzimidazole, do not easily rinse off the copper surface after completion of the cleaning process. Such additives therefore remain on the surface sought to be cleaned, and result in contamination of the integrated circuits. Contamination of the integrated circuit can adversely increase the electrical resistance of contaminated areas and cause unpredictable conducting failure within the circuit.
Other antioxidant (sacrificial) chemistries, such as catechol etc., have known to have bath life issues.
More work has been done and summarized as follows.
U.S. Pat. No. 6,755,989 describes a semiconductor wafer cleaning formulation, including 1-21 wt % fluoride source, 20-55 wt % organic amine(s), 0.5-40 wt % nitrogenous component, e. g., a nitrogen-containing carboxylic acid or an imine, 23-50 wt % water, and 0-21 wt % metal chelating agent(s). The formulations are useful to remove residue from wafers following a resist plasma ashing step, such as inorganic residue from semiconductor wafers containing delicate copper interconnecting structures.
U.S. Pat. No. 6,224,785 describes a aqueous ammonium fluoride and amine containing compositions for cleaning inorganic residues on semiconductor substrates. The semiconductor wafer cleaning formulation for use in post plasma ashing semiconductor fabrication comprising the following components in the percentage by weight ranges shown: Ammonium fluoride and/or a derivative thereof; 1-21 wt %; an organic amine or mixture of two amines; 20-55 wt % water; 23-50 wt % a metal chelating agent or mixture of chelating agents. 0-21 wt %
U.S. Pat. No. 7,521,406 describes a microelectronic cleaning compositions for cleaning microelectronic substrates, and particularly cleaning compositions useful with and having improved compatibility with microelectronic substrates characterized by silicon dioxide, sensitive low-K or high-K dielectrics and copper, tungsten, tantalum, nickel, gold, cobalt, palladium, platinum, chromium, ruthenium, rhodium, iridium, hafnium, titanium, molybdenum, tin and other metallization, as well as substrates of Al or Al(Cu) metallizations and advanced interconnect technologies, are provided by microelectronic cleaning compositions comprising halogen acids, salts and derivatives thereof.
It is therefore one object of the present invention to provide corrosion inhibitors for protection of copper structures on the semiconductor wafer or substrate.
It is another object of the invention to provide corrosion inhibitors that are easily rinsed off the substrate by water or other rinse medium after the completion of the residue-removal process, thereby reducing contamination of the integrated circuit.
It is another object of the present invention to provide chemical formulations (or compositions) and systems that effectively remove residue following a resist ashing step, and/or a CMP step, without attacking and/or potentially degrading delicate metal structures intended to remain on the wafer.
It is another object of the present invention to provide methods of using the corrosion inhibitors, the chemical compositions and systems that effectively remove residue following a resist ashing step, and/or a CMP step.